An increase in crude oil prices and in the last decade, coupled with ongoing concerns regarding sustainability, have greatly increased interest in producing chemicals and fuels from renewable sources. Much current industrial focus has fallen on biomass to replace petroleum feedstocks. Lignocellulosic biomass is perhaps the most promising renewable feedstock because it offers the potential to provide sustainable sugar streams from a variety of high-volume materials including agricultural and forest residuals, and high-yielding bioenergy crops such as switchgrass, miscanthus, and hybrid poplar. One attractive option for the conversion of lignocellulosic biomass into renewable fuel and chemical production is the production of levulinic acid (LA) which is a very versatile platform chemical and widely used in the cosmetic, food, and medicinal industries'.
A number of approaches have been reported for LA synthesis, including hydrolysis of acetyl succinate esters2, by acid hydrolysis of furfuryl alcohol3, and by oxidation of ketones with ozone.4 However, these methods frequently form large amounts of side products and intractable materials, or require an expensive feedstock. The most widely used approach is the dehydration of biomass or carbohydrates with acid.5-12 
Furfural is another by-product of biomass that undergoes acid dehydration. Furfural is formed by the reactions of pentose sugars in the biomass, such as xylose. There currently is a market for furfural and its derivatives, including furfuryl alcohol which is used a binder for foundry forms. The chemistry of the furfural production involves the acid-catalyzed hydrolysis of the hemicellulosic pentose fractions of biomass and consecutive cyclodehydration of the pentose monomers, with xylose being the most predominant pentose in most biomass. Conventional mineral acids, such as sulfuric acid, are generally used as the catalysts.13, 14 Within the past few years, several solid catalysts have also been introduced to catalyze xylose to furfural at a yield comparable to H2SO4.15-17 
The theoretical yield of LA from C6-sugars is 100 mol %, or 64.5 wt % due to the co-production of formic acid.18 In practice, using conventional methods, actual yield of LA from biomass rarely exceeds about 66% of the theoretical value (and is often much less). These lower yields are due to the formation of undesired black insoluble-materials called humins. The harsh acidic dehydration conditions utilized to hydrolyze and dehydrate hexoses to form LA from hexoses also hydrolyzes and dehydrates pentoses in the biomass to furfural, as shown in FIG. 1. In conventional approaches, the conditions are harsh enough that the furfural will further degrade and react with soluble saccharides forming solid humins. This loss of material both potentially lowers the LA yield as well as eliminates a value-added stream of furfural.
Thus, there remains a long-felt and unmet need to maximize the production of LA from biomass by minimizing the production of unwanted by-products such as humins.